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Organ Systems III > Vision 1 > Flashcards

Vision 1 Flashcards

1
Q

What is the eyeball derived from?

A

The embryonic brain.

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2
Q

What part of the neural tube becomes the cerebral hemispheres and the eyes?

A

Rostral

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3
Q

What ate the neural and pigmented layers of the retina derived from?

A

Optic vesicle.

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4
Q

What are the sclera and choroid derived from?

A

Embryonic menengeal tissues.

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5
Q

What is the lens derived from?

A

Ectoderm (not neural tissue).

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6
Q

What does the vitreous body contain in the embryo?

A

Hyluronic acid and type II collagen fibrils (slowly replaced)

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7
Q

What vestige of the hyloid artery is used to nourish the embryonic lens?

A

Hyloid canal

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8
Q

What are visual specs, reminants of the hyloid artery, that are too large to be phagocytosed?

A

Floaters

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9
Q

What are the 3 layers of the eyeball?

A

Fibrous coat, vascular coat, nervous coat

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10
Q

What is the fibrous coat homologous to?

A

Dura

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11
Q

What is the vascular coat homologous to?

A

Arachnoid and pia

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12
Q

What is the nervous coat homologous to?

A

CNS

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13
Q

Where do the extrinsic muscles of the eye insert?

A

Sclera

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14
Q

What is sclera?

A

Dense, white CT

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15
Q

What is contiguous to the sclera but clear to allow light to pass through to the retina?

A

Cornea

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16
Q

How does the cornea get nutrients?

A

Through diffusion of the aqueous humor

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17
Q

What 3 structures regulate the refraction of light?

A

Lens, ciliary body, and iris

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18
Q

What is the choroid?

A

Layer of anastomoses

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19
Q

What makes up the vascular coat?

A

Choroid and structures for regulation of light refraction

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20
Q

Most refraction of light is done by what structure?

A

The cornea

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21
Q

The remaining refraction of light not done by the cornea is variably controlled by what?

A

The lens

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22
Q

What is the function of the curvature of the lens and cornea?

A

refract radially separating rays of light at different degrees. This causes the light rays to converge back to a point.

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23
Q

How does the lens get its nutrients?

A

From the aqueous humor, through diffusion.

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24
Q

How does the lens control light refraction?

A

By changing its convexity.

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25
Q

Increased convexity of the lens focuses the light from a closer source for what?

A

near vision

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26
Q

decreased convexity focuses the light from a more distant source for what?

A

far vision

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27
Q

Where does the lens focus light?

A

Onto a point on the retina.

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28
Q

Light from what sources diverges more and requires greater refraction and lens contraction

A

nearby

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29
Q

Light from what sources is close to parallel and requires less refraction by the lens

A

far

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30
Q

What affects where the lens focuses light?

A

Eyeball length

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31
Q

What is it called when the eyeball is too long and light is focused in front of the retina?

A

Myopia (near sighted)

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32
Q

What is it called when the eyeball is too short and light is focused behind retina?

A

Hyperopia (far sighted)

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33
Q

What two things Resting is convexity of lens

is maintained by?

A

Suspensory ligaments from the ciliary body and internal elastic fibers.

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34
Q

What produces an inherent tendency of the lens to bulge, i.e. increase the convexity of the lens?

A

internal elastic fibers

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35
Q

What makes the lens capsule elastic?

A

Collagen IV and glycoprotein

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36
Q

What produces new cells during life?

A

Germinal zone

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37
Q

After migration from germinal zone, what happens to the cells?

A

cells lose their nuclei and become transparent.

38
Q

What is is the age-related loss of resting convexity caused by loss of elasticity?

A

Presbyopia (far sightedness)

39
Q

What is is the reduction of vision due to opaqueness of the lens?

A

Cataracts

40
Q

Significantly, what is increased in older and in cataractous lenses?

A

Level of iron

41
Q

What are zonule fibers that extend from ciliary body to the equatorial perimeter of the lens?

A

suspensory ligaments

42
Q

What are 2 functions of the suspensory ligaments?

A

Maintain resting tension and decrease convexity of lens by outward tension along its circumference

43
Q

What alters the convexity of the lens?

A

ciliary muscles

44
Q

What is it called when the ciliary muscles actively relax suspensory ligaments to increase convexity?

A

accommodation

45
Q

Radial fibers pull ciliary processes in which direction?

A

forward

46
Q

What do circular fibers do to the lens?

A

diminish circumference of suspensory ligaments

47
Q

Which part(s) of the ciliary muscle relax the tension in the suspensory ligaments allowing the intrinsic elasticity of the lens to increase its convexity for close vision.

A

both

48
Q

Ciliary processes secrete what into anterior and posterior chambers

A

aqueous humor

49
Q

What are the anterior and posterior chambers partitioned by?

A

the iris

50
Q

What absorbs humor into veins?

A

Schlemm’s canal (sinus venosus sclerae)

51
Q

What disease causes the build up of fluid pressure due to inadequate drainage into Schlemm’s canal?

A

glaucoma

52
Q

What contains pigmented striations of CT,

blood vessels & smooth muscle?

A

the iris

53
Q

What is stroma?

A

CT with melanocytes

54
Q

What absorbs and refracts different frequencies (colors)?

A

Melanin

55
Q

What is continuous on posterior surface of iris; completely absorbs all light restricting incoming light to within pupil?

A

Pigment epithelium

56
Q

What is a genetic trait that involves distribution of melanin pigments in the iris?

A

eye color

57
Q

What is eye color determined by?

A

Different patterns of light refraction by melanin.

58
Q

If there are no blue or green iris pigments, what causes blue eyes?

A

melanin is mostly on the deep surface

of the iris and Blue spectrum is maximally refracted from the deep surface and eyes appear blue

59
Q

What causes brown or green eyes?

A

melanin is more evenly distributed through the iris CT which refracts more of the light spectrum producing more color possibilities

60
Q

What colors are brown eyes a combination of?

A

blue, green, red, and yellow light

61
Q

What structure controls the aperture of the pupil?

A

The iris

62
Q

What affects the range of focus?

A

Smaller pupils increase the range of focus; wider pupils decrease it.

63
Q

Which muscle constricts the pupil and reduces incoming light?

A

Sphincter Pupillae

64
Q

Sphincter pupillae is sympathetic or parasympathetic?

A

parasympathetic

65
Q

Which muscles Opens pupil & increases incoming light?

A

Dilator pupillae

66
Q

Dilator pupillae are sympathetic or parasympathetic?

A

sympathetic

67
Q

Where do parasympathetic nerves of the pupil travel?

A

Along oculomotor nerve (CNIII)

68
Q

Where is the ciliary ganglion? Parasympathetic or sympathetic?

A

Posterior of the eyeball; parasympathetic

69
Q

Where does sympathetic activity arise from?

A

Upper thoracic levels of the spinal cord

70
Q

Which structure consists of postganglionic neurons that project axons along arteries to the iris?

A

Superior cervical ganglion.

71
Q

What constricts the pupil?

A

Parasympathetics

72
Q

What contacts the lens, sympathetic or parasympathetic?

A

Parasympathetics

73
Q

Where are parasympathetic preganglionic neurons located?

A

Within the Edinger-Westphal nucleus.

74
Q

What is the name of one of the nuclei of the oculomotor nerve that contains the parasympathetic preganglionic neurons?

A

Edinger-Westphal nucleus

75
Q

Whereis the Edinger-Westphal nucleus?

A

Midbrain

76
Q

What 2 things do parasympathetic postganglionic neurons in the ciliary ganglion activate?

A

Sphincter pupillae to constric the pupil and ciliary muscle to contract the lens.

77
Q

What is the function of the pupillary light reflex?

A

Maintain homeostatic level of light entering the eye

78
Q

_________ ganglion cells in the retina respond to ambient light.

A

Melanopsin

79
Q

_______ coordinates both eyes.

A

Pretectal nucleus

80
Q

What is the path of the consensual pupillary response?

A

Light to melanopsin ganglion cells to pretectal nucleus to Edinger-Westphal nucleus to ciliary ganglion to pupil

81
Q

What is the consensual pupillary response?

A

Constriction of both pupils in response to light shone in one eye

82
Q

What does sympathetic activity increase?

A

Light entry into the eye

83
Q

Which neurons innervate the superior cervical ganglion (SCG) cells?

A

preganglionic neurons in T1,2

84
Q

What 2 things does the postganglionic SCG neurons activate?

A

Dilator pupillae to open the pupil and tarsal muscle to raise the upper eyelid

85
Q

What are 2 things the sympathetic control of the iris and upper eyelid regulated by?

A

Local reflexes and descending influences from the limbic system and hypothalamus during an emotional state.

86
Q

What muscle is a smooth muscle just deep to the levator palpebrae superioris and attaches to the tarsal plate in the eyelid?

A

Tarsal muscle

87
Q

What is the tarsal muscle innervated by?

A

Sympathetic nerves

88
Q

What is the function of the sympathetic control of the tarsal muscle?

A

To raise upper eyelid in emotional states

89
Q

What is the name for a drooping eyelid?

A

Ptosis

90
Q

What is the name for the condition that includes ptosis?

A

Horner’s syndrome

Organ Systems III (13 decks)

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